WASHINGTON (CNN) --Key portions of a joint congressional investigative report on the September 11 terrorist attacks that will be released this week will be kept classified by the Bush administration for political, not security, reasons, Sen. Bob Graham said Sunday.

"The classification had more to do with [any given] agency wishing to avoid embarrassment by the disclosure of their actions or inactions rather than the protection of some national security interest," Graham said on CBS's "Face The Nation."

The Florida Democrat said key sections of the 800-page report of the joint investigation by the House and Senate intelligence committees that are being kept under wraps deal with the role of foreign governments in the events leading up to September 11.

Graham, who is running for the 2004 Democratic presidential nomination, was one of the leaders of the joint investigation into intelligence and security failures leading to the September 11, 2001 attacks.

He said the part of the report that deals with the activities of foreign governments "is the most classified section." Because of that, Graham said he could not identify the countries.

"I do not want to take a detour to the federal penitentiary in my campaign for president," said Graham, who was chairman of Senate Select Committee on Intelligence last year.

Fifteen of the 19 hijackers who carried out the September 11 attacks were Saudi nationals, some of whom are believed by U.S. authorities to have received assistance from Saudi Arabia-based charities while they were living in the United States.

While not identifying the country or countries identified in the report, Graham said, "I will say that the foreign government went well beyond facilitating charitable giving to terrorists.

"There was also direct governmental involvement with some of the terrorists. And an unanswered question is, Was the same assistance provided to the other 19 terrorists?"

Graham said "it's always been curious to me how 19 people -- many of whom had very little previous affinity with the United States, several of whom did not speak English -- could come into the United States, hide themselves for periods of 18 months or longer, plan, practice and then executive a very complicated terrorist attack without being disclosed."

Saudi officials have repeatedly denied they knowingly helped the September 11 terrorists and insist they have assisted U.S. efforts to fight terrorism, both before and after the attacks.

The Bush administration has also said Saudi Arabia has been an ally in the war against terrorism.

Graham, who has been a critic of President Bush's Iraq policy, also said the congressional investigation turned up "no connection" between Saddam Hussein and September 11 and "very limited evidence" of a relationship between his regime and al Qaeda, either before or after the attacks.

"In fact, there was an enmity between Osama bin Laden and Saddam Hussein based on their quite different views of the future of the Islamic world," Graham said.